This invention relates generally to an endoscope or borescope for providing a full color video image of a generally inaccessible region and, in particular, to a highly compacted imager assembly for use in the viewing head of an endoscope or a borescope.
Sheldon in U.S. Pat. No. 2,764,149 discloses an endoscope for providing a full color video picture of a target situated within a body cavity. The viewing head of the Sheldon device, that is, the section of the instrument which is inserted into the body cavity, contains a rather bulky vidicon tube and a complex three color lighting system which requires that the head be rather large in order to house the various components. Consequently, the Sheldon device can only be used where the receiving cavity is correspondingly large. Kakinuma in U.S. Pat. No. 4,074,306 discloses an improved full color endoscope system in which the light source is taken out of the head and the vidicon tube is replaced by a solid state image sensor. In this new arrangement, the light of three primary colors needed to both illuminate the target and to provide color separation is transmitted into the head via a fiber bundle. Although the Kakinuma device reduces the size and the number of components needed in the viewing head, this advantage may easily be lost through poor packaging.